The present invention relates to a wafer holding plate used for wafer grinding apparatuses and a method for manufacturing the same.
Apparatuses for grinding the surface of a semiconductor wafer, such as a lapping machine or a polishing machine, are known in the prior art. A typical wafer grinding apparatus includes a table, which is fixed to a cooling jacket, and a wafer holding plate. The plate has a wafer adhering surface to which an adhesive, such as a thermoplastic wax, is applied. The adhesive attaches a semiconductor wafer to the plate.
Since the wafer adhering surface is flat, the adhesive must be relatively thick to ensure adhesion of the semiconductor wafer. It is difficult to apply the adhesive uniformly. As a result, parallelism between the wafer adhering surface and the semiconductor wafer is not achieved, which causes the semiconductor wafer to be held obliquely. Therefore, it is difficult to achieve highly accurate grinding.
Furthermore, if the surface of the plate is rough, the lands and pits of the plate surface are transferred to the rear surface of the wafer (the surface adhered to the plate) when the plate holding the wafer is pressed against a grinding surface. This decreases the accuracy and quality of the semiconductor wafer. Additionally, production efficiency decreases because wafers have to be reground to correct dimensions.
It is an object of the present invention to provide a wafer holding plate for a wafer grinding apparatus that can manufacture a semiconductor wafer with high accuracy and high quality.
To achieve the above object, the present invention provides a wafer holding plate used in a wafer grinding apparatus. The plate includes a substrate having a wafer adhering surface to which a semiconductor wafer is adhered by an adhesive. The wafer adhering surface includes a mirror-like surface in which a groove pattern is formed.
A further aspect of the present invention provides a wafer holding plate used in a wafer grinding apparatus. The plate includes a substrate having a wafer adhering surface to which a semiconductor wafer is adhered by an adhesive. The wafer adhering surface includes a groove pattern. The groove pattern includes grooves having curved edges.
Another aspect of the present invention provides a method for manufacturing a wafer holding plate used in a wafer grinding apparatus. The method includes grinding a surface of a substrate to which a semiconductor wafer is adhered by an adhesive, masking the ground surface with a predetermined pattern, and blasting the wafer adhering surface with particles to form a groove pattern.
A further aspect of the present invention provides a method for manufacturing a wafer holding plate used in a wafer grinding apparatus. The method includes blasting a wafer adhering surface of a substrate with particles to form grooves and to simultaneously round edges of the grooves. A semiconductor wafer is adhered to the completed wafer adhering surface with adhesive.